LACTATE, N-ACETYLASPARTATE, CHOLINE AND CREATINE CONCENTRATIONS, AND SPIN-SPIN RELAXATION IN THALAMIC AND OCCIPITOPARIETAL REGIONS OF DEVELOPING HUMAN BRAIN

Previous studies of the brains of normal infants demonstrated lower la ctate (Lac)/choline (Cho), Lac/creatine (Cr), and Lac/N-acetylaspartat e (Naa) peak-area ratios in the thalamic region (predominantly gray ma tter) compared with occipitoparietal (mainly unmyelinated white matter ) values. In the present study, thalamic Cho, Cr, and Naa concentratio ns between 32-42 weeks' gestational plus postnatal age were greater th an occipito-parietal: 4.6 +/- 0.8 (mean +/- SE), 10.5 +/- 2.0, and 9.0 +/- 0.7 versus 1.8 +/- 0.6, 5.8 +/- 1.5, and 3.4 +/- 1.1 mmol/kg wet weight, respectively: Lac concentrations were similar, 2.7 +/- 0.6 and 3.3 +/- 1.3 mmol/kg wet weight, respectively, In the thalamic region, Cho and Naa T(2)s increased, and Cho and Lac concentrations decreased , during development. Lower thalamic Lac peak-area ratios are principa lly due to higher thalamic concentrations of Cho, Cr, and Naa rather t han less Lac. The high thalamic Cho concentration may relate to active myelination; the high thalamic Naa concentration may be due to advanc ed gray-matter development including active myelination. Lac concentra tion is higher in neonatal than in adult brain.